Counter strike source
This game is so fun it has severs that are made by people from all over the world and you can play on them or make your own
Different mods are every were you just have to look for them
there are many mods and maps that are different then the others
like surf maps that you have to ride the pole to the plat from to teleport to the enemies base if you fall your dead. or in jail. so be careful
There are zombie mod severs that make a player into a zombie and he has to knife someone to turn them into a zombie so RUN!!!
This one is more of a hiding mod then killing you can build a barricade out of pop machines and tables and the zombies have to get in.
Next one…down here
There are sport games that you score a goal and the other team gets killed like the zombies ha-ha that’s its called ka_soccer